Process for desulphurization of heavy petroleum residues using electric current

ABSTRACT

A process for desulphurization of heavy petroleum residues comprises heating thereof to a temperature of from 190° to 200° C., passing a 4-20V electric current through the heated petroleum heavy residues and adding Fe 2  O 3  and/or Pb 3  O 4  and Ba(OH) 2  thereto in a weight ratio of the components of 1-10:1-20 respectively; in the case of using Fe 2  O 3  and Pb 3  O 4  simultaneously, their weight ratio is equal to 2-9:1-5 respectively.

FIELD OF THE INVENTION

1. Background of the Invention

The present invention relates to processes for desulphurization of heavypetroleum residues.

These heavy petroleum residues find an extensive use in industry. Suchheavy resides can be exemplified, by residual asphalt, boiler fuel,petroleum oils widely used as fuels, lubricants, as well as bitumens.Bitumens are employed in road construction, hydraulic engineering ashydroinsulation, roofing and anticorrosion materials, as well as abinder in the manufacture of bitumen-containing and heat-insulationmaterials. Bitumens also comprise raw materials in the production ofpetroleum coke.

2. Description of the Related Art

This wide application of heavy petroleum residues is possible owing to awide range of useful properties thereof: heat- and frost-resistance,plasticity, good adhesion-cohesion characteristics, resistance inaggressive media, high dielectric properties. However, at a long-timeexposure to high temperatures (up to 150° C.) a negative influence ofsulphur compounds contained in petroleum residues starts to manifestitself. Sulphur compounds cause corrosion of steel structures.Electrical resistance of coatings, e.g. bitumen ones, gets substantiallydecreased upon exposure to a humid medium at an elevated temperature dueto the presence of such compounds, i.e. sulphur compounds in heavypetroleum residues considerably lower their physico-mechanicalcharacteristics. There are a number of processes aimed at reduction ofthe content of sulphur compounds (desulphurization of heavy petroleumresidues by way of treatment thereof with various agents). Thus, knownin the art is a process for desulphurization of petroleum oils (BritishApplication No. 2,019,433; 1979). According to this process, petroleumoil is charged into a container and heated to a temperature of 120 to350° C., whereafter sulphohydrates or hydrates of alkali metal sulphides(cesium, rubidium, potassium, sodium or lithium) are added thereto.

The process of desulphurization is conducted in the atmosphere ofhydrogen under a pressure of up to 400kg/cm², the desulphurized productis separated from hydrates of an alkali metal hydroxide and fromhydrates of an alkali metal sulphide or from a mixture of both. Therecovery of contaminants from desulphurized petroleum oils is effectedby passing steam therethrough.

This process makes it possible to obtain petroleum oils with asufficiently low content of sulphur compounds; however, the process israther complicated and expensive, since, it necessitates the use ofhydrogen under a high pressure.

In another process heavy petroleum residues such as boiler fuel arecontinuously supplied into a reactor, wherein a stationary bed of acatalyst is provided. Simultaneously with the starting product hydrogenis supplied at a temperature within the range of from 315 to 455° C.under a pressure of from 14 to 700 atm. A stationary bed of catalystparticles contains 10 to 20% by weight of molybdenum oxide and/or 1 to8% by weight of cobalt oxide supported on an oxide carrier. The productwith a reduced content of sulphur compounds is withdrawn from thereactor (USSR Pat. No. 638267, 1977).

This process makes it possible to lower the content of sulphur by80-85%, but this process also features a complicated scheme, since itnecessitates the use of hydrogen; furthermore, preparation of theemployed catalyst is associated with substantial process difficulties.

DISCLOSURE OF THE INVENTION

The present invention is directed to the provision of such a process fordesulphurization of heavy petroleum residues which would make itpossible to considerably lower the content of sulphur compounds in thestarting product following a simplified procedure.

This object is accomplished by that in the process for desulphurizationof heavy petroleum residues comprising heating of heavy petroleumresidues to a temperature of 190°-200° C., their treatment by metaloxides and hydroxides and separation of disulphrized residues accordingto the present invention a DC current of 4-20V is passed through heatedheavy petroleum residues and as metal oxides use is made of Ba(OH)₂ at aweight ratio of a proportionate range of Fe₂ O₃ :Ba(OH)₂ of 1-10 partsFe₂ O₃ to 1-20 parts BA(OH)₂ ; of a proportionate range of Pb₃ O₄:Ba(OH)₂ of 1-10 parts Pb₃ O₄ to 1-20 parts Ba(OH)₂ ; of a proportionaterange of Fe₂ O₃ :Pb₃ O₄ :Ba(OH)₂ when Fe₂ O₃ and Pb₃ O₄ are usedsimultaneously with Ba(OH)₂ of 2-9 parts Fe₂ O₃ to 1-5 parts Pb₃ O₄ to1-20 parts Ba(OH)₂.

As the heavy petroleum residues it is possible to use, for example,boiler fuel, residual asphalt, petroleum oils, bitumen. At a selectedtemperature and voltage the starting stock acquires properties of aNewtonian fluid, wherein solid fractions (metal oxides and hydroxides)can readily move. Upon application of an electric field the process ofelectrolysis starts in molecules and the most complete neutralization ofsulphur compounds takes place.

The selected amounts of metal oxides and hydroxides are necessary andsufficient to ensure the maximum degree of desulphurization of sulphurcompounds contained in the starting product.

SUMMARY OF THE INVENTION

The process according to the present invention makes it possible tolower the content of sulphur compounds by 90-95%. The processnecessitates no use of a special equipment or of expensive hydrogen. Theprocess is economically efficient. In the Table hereinbelowphysico-mechanical characteristics of some petroleum residues before andafter their desulphurization by the process according to the presentinvention are shown.

The service life of pipelines insulated by the bitument desulphurized bythe process according to the present invention is extended from 10 to 25years.

                  TABLE                                                           ______________________________________                                                          Bitumen                                                     No.  Characteristics    Initial Desulphurized                                 1    2                  3       4                                             ______________________________________                                        1.   Sulphur content, % 2.47    0.3                                           2.   pH before heat-treatment                                                                         7.05     7.05                                              pH after heat-treatment at                                                                       3.0     7.0                                                150° C. for 1,000 hours                                           3.   Volume resistivity, Ohm.cm                                                                       .sup. 10.sup.14                                                                       10.sup.14                                     4.   Volume resistivity, Ohm.cm,                                                                      10.sup.3                                                                              10.sup.13                                          after thermo-humid treatment                                                  at 75 ± 5° C. for 250 hours                                    ______________________________________                                                     Residual Asphalt                                                                         Petroleum Oils                                        Boiler Fuel             Desul-         Desul-                                               Desul-          phur-        phur-                              No.  Initial  phurized Initial                                                                              ized  Initial                                                                              ized                               1    5        6        7      8     9      10                                 ______________________________________                                        1.    2.25     0.29     2.33   0.28  1.97   0.27                              2.   7.0      7.0      7.1    7.1   7.0    7.0                                     3.0      7.0      3.0    7.0   3.0    7.0                                3.   10.sup.13                                                                              10.sup.13                                                                              10.sup.13                                                                            10.sup.13                                                                           10.sup.11                                                                            10.sup.11                          4.   10.sup.3 10.sup.12                                                                              10.sup.3                                                                             10.sup.12                                                                           10.sup.3                                                                             10.sup.10                          ______________________________________                                    

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The process is technologically simple and can be practiced in thefollowing manner.

Into a vessel provided with a stirrer heavy petroleum residues arecharged and heated to a temperature of 190°-200° C., followed by passingelectric current with a voltage of 4-20V through the product. Then apowder-like mixture is added which consists of Fe₂ O₃ and/or Pb₃ O₄ andBa(OH)₂ in selected proportions. The desulphurized petroleum residuesare separated from impurities by any conventional method, for example bycentrifugation or sedimentation.

For a better understanding of the present invention some specificExamples are given hereinbelow by way of illustration.

EXAMPLE 1

Into a vessel provided with a stirrer 1,000 g of bitumen containing2.47% of sulphur are charged. The bitumen is heated to the temperatureof 190° C., whereafter electric current of 12V voltage is passed throughthe heated bitumen. Then a powderlike mixture consisting of Fe₂ O₃ andBa(OH)₂ in the weight ratio of the components equal to 1:2 respectivelyis added thereto. The process duration is 45 minutes, whereafter thecurrent source is switched-off and the stirrer is stopped. The processduration is 45 minutes, whereafter the current source is switched-offand the stirrer is stopped. The thus-obtained mass is kept at theabove-mentioned temperature for one hour; as a result, two layers areformed: the upper layer - liquid desulphurized bitumen with the contentof sulphur of 0.3% and the lower layer - solid impurities which are thenseparated.

EXAMPLE 2

The experiment is carried out under the conditions specified in Example1 hereinabove, except that the starting bitumen contains 4.86% ofsulphur; it is heated to the temperature of 200° C. and the voltage is4V. The weight ratio of the components Fe₂ O₃ :Ba(OH)₂ =8:9. As aresult, the content of sulphur in the final product is equal to 1.98%.

EXAMPLE 3

Into a vessel provided with a stirrer 1,000 g of a residual asphalt arecharged which contains 2.33% of sulphur. The residual asphalt is heatedto the temperature of 195° C., whereafter electric current of 8V voltageis passed through the heated residual asphalt and then a powder-likemixture is added thereto which consists of Fe₂ O₃ and Ba(OH)₂ employedin the weight ratio therebetween of 1:2 respectively.

The process duration is 60 minutes. Then the electric current source isswitched-off and the stirrer is stopped.

The obtained mass is kept at the above-specified temperature for onehour so that two layers are formed: the liquid layer--desulphurizedresidual asphalt with the content of sulphur of 0.27%; the lower layercomprises solid impurities which are then separated.

EXAMPLE 4

Into a vessel provided with a stirrer 1,000 g of bitumen containing5.05% of sulphur are charged. The bitumen is heated to the temperatureof 190° C., whereafter electric current of 15V voltage is passed throughthe heated bitumen. Then a powderlike mixture consisting of Pb₃ O₄ andBa(OH)₂ in the weight ratio of 4:5 between the components respectivelyis added thereto. The process duration is 45 minutes. Then the electriccurrent source is switched-off and the stirrer is stopped. Thethus-obtained mass is kept at the above-specified temperature for onehour so that two layers are formed: the upper layer comprises liquiddesulphurized bitumen with a content of sulphur of up to 2.09% and thelower layer - solid impurities which are then separated.

EXAMPLE 5

The experiment is carried out under the same conditions as thosedescribed in the foregoing Example 4, except that the content of sulphurin the starting bitumen is 2.79%, the process temperature is 200° C.,voltage 4V, weight ratio of the components Pb₃ O₄ and Ba(OH)₂ =7:10. Asa result, the content of sulphur in the desulphurized bitumen is 0.74%.

EXAMPLE 6

Into a vessel provided with a stirrer 1,000 g of boiler fuel containing2.25% of sulphur are charged. The mazout is heated to the temperature of190° C., whereafter electric current of 15V voltage is passed throughthe heated boiler fuel and then a powderlike mixture consisting of Fe₃O₃, Pb₃ O₄ and Ba(OH)₂ is added thereto in the weight ratio between thecomponents of 2:1:2 respectively.

The process duration is 50 minutes. Then the electric current source isswitched-off and the stirrer is stopped. The resulting mass is kept atthe above-specified temperature for one hour to form two layers: theliquid layer comprising desulphurized boiler fuel with the content ofsulphur of 0.29% and the lower layer comprising solid impurities whichare then separated.

EXAMPLE 7

Into a vessel provided with a stirrer 1,000 g of bitumen containign3.29% of sulphur are charged. Bitumen is heated to the temperature of200° C., whereafter electric current of 20V voltage is passed throughthe heated bitumen and then a powderlike mixture consisting of Fe₂ O₃,Pb₃ O₄ and Ba(OH)₂ is added thereto in the weight ratio of theabove-mentioned components of 2:1:3 respectively. The process durationis 45 minutes, whereafter the electric current source is switched-offand the stirrer is stopped. The resulting mass is kept at theabovespecified temperature for one hour to give two layers: the upperlayer comprising liquid desulphurized bitumen with the content ofsulphur of 1.02% and the lower layer comprising solid impurities whichare then separated.

EXAMPLE 8

The experiment is conducted under conditions described in Example 7,except that the content of sulphur in the starting bitumen is 2.91%, theprocess temperature is 195° C., voltage 4V, the weight ratio between thecomponents Fe₂ O₃, Pb₃ O₄ and Ba(OH)₂ is equal to 4:5:12 respectively.As a result, the content of sulphur in the desulphurized bitumen is0.52%.

EXAMPLE 9

Into a vessel provided with a stirrer 1,000 g of petroleum oilcontaining 1.97% of sulphur are charged. The oil is heated to thetemperature of 190° C., whereafter electric current of 6V voltage ispassed through the heated oil and then a powder-like mixture consistingof Fe₂ O₃, Pb₃ O₄ and Ba(OH)₂ is added thereto in the weight ratiobetween the components of (:1:20 respectively.

The process duration is 45 minutes, whereafter the electric currentsource is switched-off and the stirrer is stopped. The thus-obtainedmass is kept at the above-specified temperature for one hour so that twolayers are formed: the upper layer comprising liquid desulphurized oilwith the content of sulphur of 0.27% and the lower layer comprisingsolid impurities which are separated.

INDUSTRIAL APPLICABILITY

Heavy petroleum residues desulphurized by the process according to thepresent invention can be useful in industry as a fuel, lubricants,hydro-insulation, roofing, corrosion-preventing and heat-insulationmaterials.

We claim:
 1. A process for desulphurization of heavy petroleum residuescomprising heating said heavy petroleum residues to a temperature of 190to 200° C., introducing oxides and hydroxides of metals, passing anelectric current of 4-20V DC through the heated heavy petroleumresidues, using as the oxides Fe₂ O₃ and/or Pb₃ O₄ and as the hydroxideBa(OH)₂ in a weight ratio of a proportionate range of Fe₂ O₃ :Ba(OH)₂ of1-10 parts Fe₂ O₃ to 1-20 parts Ba(OH)₂ ; of a proportionate range ofPb₃ O₄ :Ba(OH)₂ of 1-10 parts Pb₃ O₄ to 1-20 parts Ba(OH)₂ ; of aproportionate range of Fe₂ O₃ :Pb₃ O₄ :Ba(OH)₂ when Fe₂ O₃ and Pb₃ O₄are used simultaneously with Ba(OH)₂ of 2-9 parts Fe₂ O₃ to 1-5 partsPb₃ O₄ to 1-20 parts Ba(OH)₂, and separating desulphurized residues. 2.A process as claimed in claim 1, characterized in that the process isconducted with a weight ratio of Fe₂ O₃ to Ba(OH)₂ being 1-8 to 2-10respectively.
 3. A process as claimed in claim 1, characterized in thatthe process in conducted with a weight ratio of Pb₃ O₄ to Ba(OH)₂ being4-7 to 5-10 respectively.
 4. A process as claimed in claim 1,characterized in that the process is conducted with a weight ratio ofFe₂ O₃ to Pb₃ O₄ to Ba(OH)₂ being 2-9 to 1-5 to 2-20 respectively.